1. Field of the Invention
The present invention relates to a duct having a cylindrical shape for circulating a heated air, and a projector.
2. Description of Related Art
Conventionally, a projector that modulates a light beam irradiated by a light source in accordance with image information to form an optical image by way of a modulator and projects the optical image in an enlarged manner has been known (e.g., refer to JP2002-365728A).
The projector has an axial-flow exhaust fan that discharges a heated air heated by the light source to the outside of the projector with the temperature of the heated air becoming higher along with the higher luminance of the light source. The axial-flow exhaust fan is disposed near the light source to draw in the heated air inside the projector and to discharge the indrawn air from an exhaust port formed on an exterior case of the projector. Additionally, a plurality of blades inclined at a predetermined angle are provided on the exhaust port to guide an exhaust airflow in a predetermined direction. With the blades, the heated air is discharged in a direction in which a viewer of a projected image around the projector nor the projected image projected by the projector are not presented.
However, in the above-described arrangement, when a part of the light beam irradiated by the light source is deviated from an illumination optical axis to leak inside the projector, only the incident light beam orthogonal to the exhaust port can be shielded by the blades, but the incident light beam in an inclination direction of the blades cannot be shielded. Accordingly, the light beam leaked via the exhaust port in the inclination direction of the blades may cause the viewer feeling uncomfortable when he/she views the projected image projected by the projector.